Chemical anchoring is a technique for fastening to concrete and similar substrates that provides more flexibility than mechanical anchoring. A mechanical anchor, such as a sleeve anchor, Dynabolt®, wedge anchor or drop-in anchor, is inserted in the concrete and expands upon tightening.
Steel reinforcement bars or rebars are used to improve the tensile strength of the concrete, since concrete is very weak in tension, but is strong in compression. Steel is only used as rebar because elongation of steel due to high temperatures (thermal expansion coefficient) nearly equals to that of concrete.